Method for producing a high bulk filamentary material



Jan. 4, 1966 SWERDLQFF ETAL 3,226,795

METHOD FOR PRODUCING A HIGH-BULK FILAMENTARY MATERIAL Original Filed Aug. 12, 1959 F/GJ United States Patent 3,226,795 METHOD FOR PRODUCING A HIGH BULK FILAMENTARY MATERIAL Jack Swerdlolf, Miami, Fla., Ezra B. Larsen, Boulder,

Colo., and Adriaan J. Troelemau, Narrows, Va., assignors to Celanese Corporation of America, New York, l I.Y., a corporation of Delaware Original application Aug. 12, 1959, Ser. No. 833,230, now Patent No. 3,093,142, dated June 11, 1963. Divided and this application May 23, 1962, Ser. No. 203,672 The portion of the term of the patent subsequent to Jan. 24, 1978, has been disclaimed 7 Claims. (Cl. 28-72) The present invention relates to high bulk filamentary material. More particularly, it relates to filamentary material, i.e. continuous filaments or staple fibers, of organic acid esters of cellulose, which is especially suited as a filtering, filling or stufiing material. The present invention also relates to the process or method used for manufacturing the high bulk filamentary material, and to. the application of this material in the trade. r

Synthetic filamentary materials such as cellulose esters are formed by extrusion of solutions through orifices in a member known as a jet. The orifices are small and usually circular so that the resulting filamentary materials are bulbous or generally circular in cross-section, although the surface of the said materials is normally crenulated and irregular. Consequently, the specific volume or voltime per unit mass of such material is comparatively low, so that a predetermined weight will occupy less volume than that desired for certain applications, or if placed in an enclosure of a predetermined volume they will pack less .tightly than is desired.

It is an object of the present invention to provide filamentary materials of comparatively high specific volume, i.e. of high bulk, and to provide a process for manufacturing these filamentary materials.

. It is another object of the present invention to provide articles such as pillows and mattressesfilled or stuffed withhigh-bulk materials, which articles will be light in weight and comfortable but nonetheless moderately firm and resilient.

7 Another object of the invention 'is to provide improved filter materials and articles containing saidfilter materials.

- :Other objects and advantages of the invention will become apparent from the detailed description and claims which follow." i i In accordance with the invention, filament-forming materials such as celluloseesters are spun, i.e. extruded, through orifices in jets and the filamentary material is then subjected to at least two crimping operations to impart thereto a non-rectilinear configuration. The first crimp-ing:

operation increases the bulk or specific volume because adjacent filaments cannot pack as closely. The second crimping operation introduces additional crimps and these deformations willlie in a plurality of planes directed at an angle to that generally defined by the first crimping. Thus the filamentary material is three dimensional and has a still higher specific volume. 1 2

Before each crimping, which ispreferably effected by use of astuffing box so as to avoid tearing of the filamentary material suchas results when using a gear toothed crimper which pulls the filaments into their new shapes, the filamentary material .is moistened with 'water" ora'n aqueous solution of a softening agent. 'In. addition to filamentary material is spun through spinning jets having avoiding weakenin-gjof. the filaments, the use of a plurality Patented Jan. 4, 1966 non-circular apertures so that the filamentary material after crimping will have high resilience and a specific volume at least 20% greater than that of a mass of crimped circular filaments of equal denier, i.e. of equal cross-sectional area. The preferred filamentary cross-section is Y-shaped, such as is produced by spinning through triangular orifices. However, mixtures of filaments spun through diiierently shaped non-circular orifices may be used. Minor amounts of filaments spun through circular orifices can be included. Accordingly, if filaments spun through circular orifices are included, they should be used only in such an amount as will still leave the total specific volume after crimping at least 20% greater than that of a mass spun wholly through circular orifices.

In accordance with another aspect of the invention a tow or large bundle of the bulky filamentary material is formed into cigarette filters by more or less conventional steps such as opening the tow, applying about 2 to 30% by weight of a plasticizer whose composition depends upon the composition of the tow, e.g. glycerol triacetate, triethyl citrate, dimethoxy ethyl phthalate, methyl phthalyl ethyl glycolate or the like for cellulose acetate, condensing the plasticized tow, encasing the tow in paper to form a rod about 1 inch in periphery, cutting the rod into plugs of predetermined length, and curing to effect bonding of filaments to one another by the plasticizer so as to increase the firmness of the plug, i.e. the resistance to transverse compression. The time and temperature of curing will vary inversely, and will vary with the plasticizer, e.g. several hours at room temperature will cure a cellulose acetate filter plasticized with glycerol triacetate. Because of the high bulk and resilience of the novel filaments "and tows thereof cigarettes including the novel filters are more firm than filters from conventional plugs. Alternately, to produce a plug of given length and predetermined firmness either the amount of plasticizer can be decreased or a lesser weight of filaments can be employed, with obvious advantage. The filters in the finished cigarettes generally range from about 10 to 17 mm. in length.

The invention will now be described with reference to the accompanying drawing wherein:

FIG. 1 is a schematic illustration of the process;

FIGS. 2 to 6 are cross-sectional views of difierent shapes of filaments which can be spun and processed in accordance with the invention;

FIG. 7 is a schematic perspective view of a portion of a filament having the shape shown in FIG. 2 and subjected to one crimping operation;

FIG. 8 is a perspective vector diagram for defining the spatial disposition of the filament of FIG. 7;

FIG. 9 is a schematic perspective view of a portion of the filament of FIG. 7 after being subjected to a second crimping operation;

FIG; 10 is a perspective view of a pillow, a portion being shown broken away to expose the stufling;

FIG. 11 is a perspective view of a cigarette including a filter produced from a tow processed in accordance with the present invention; and

FIG. 12 is a sketch diagrammatically defining the amplitude and number of crimps per unit length as employed herein.

Referring now more particularly to the drawing, a lubricated tow 11 of filaments of cellulose acetate is passed over a roller 12 dipping into a trough 13 containing water or a water emulsion of lubricants and softening agents. Another roller 14 flattens out the tow 11 somewhat to ensure wetting of all filaments.

The tow passes through a first stufllng box crimper 15 which crimps the tow, imparting to each filament an appearance somewhat as is shown in FIG. 7. The tow'then passes over a further roller 16 dipping into a trough 17 which contains warm water or other lubricant. .An upper roller 18 ensures Wetting of all filaments of the tow 11. Other equivalent structures such as sprays or wet felt pads may be employed to lubricate the tow. The tow next passes into a second stuffing box crimper 19 which may be of identical construction or which may be designed to produce crimps of a slightly lower amplitude, for example. The tow leaving the crimper 19 is dried and cut by cutter 20 into staple lengths 21. The filaments 22 of the tow which leaves the crimper 19 have the approximate appearance shown in FIG. 8.

The staple lengths 21 of multi-crimped cellulose acetate can be used to stuif a ticking 23 to form a pillow 24 as shown in FIG. 10. The fibers are also useful as fillings for other articles such as mattresses, comforters, jacket interlinings and the like.

In place of being cut into staple fibers, the tow leaving second crimper 19 can be baled and then used, or directly used, in making cigarette filters such as described in US. Patent 2,794,239 employing conventional apparatus (not shown). The filter plugs produced from the tow by open- I ing, plasticizing, wrapping, cutting and curing comprise generally longitudinally extending filaments 34 held inside a paper wrapper 35 which is wrapped, together with a rod of tobacco 36 inside an outer paper 37, as shown in FIG. 11.

The filaments can be Y-shaped in cross-section as shown at 22 in FIG. 2, this configuration resulting upon drying and shrinking of filaments spun through a jet having triangular orifices. The non-circular contour produces a high bulk or specific volume which is increased by the successive crimpings. The cross-sectional shape of the filaments resists bending and deformation which is particularly desirable for stufiings and battings. This resistance gives the stuffed article a resilient quality in addition to its light weight resulting from the low specific volume of the filling.

The individual filaments can be substantially circular in cross-section as shown at 25 in FIG. 3 but such filaments will havea lower specific volume than either filament 22 or filaments 26, 27 or 28 (FIGS. 4 to 6), respectively produced by spinning through slotted, square or star-shaped orifices.

The denier of the individual filaments can range from 3 or even lower to as much as 25 or even higher. Preferably, however, it lies between 5 and 10. The number of filaments per yarn end will depend upon the number of holes per jet and the number of yarns which may be gathered into a tow will depend upon-the capacity of the crimping devices and the intended end uses. For cigarette filters, the total number of filaments may be as much as 3000 to 40,000 or more and the total denier may range from about 50,000 to 250,000 or more.

The filaments preferably are treated with a lubricant or finish ranging from about 0.3 to 2.0% by weight of the filamentary material. An especially soft luxurious hand will result from use of a finishing composition comprising'one of the-cationic group of softeners such as quaternary ammonium compound, or other chemical softener imparting a similar hand. An even bulkier yarn will result by substituting as the lubricant an alkyl phosphate in mineral oil, especially compositions such as that described in Example III of Fortess et al. US. Patent No. 2,676,924 of April 27, 1954.

The cutter 20 can constitute any device known in the art, such as a reciprocating blade or a rotary cutter. The

cutter can be operated to form staple fibers-ranging in length from /2 to 8 inches, although they preferably range in length from 1 to 4 inches.

The crimpers 15 and 190m constitute an apparatusfilament 22 has a predominantly two-dimensional sinusoidal or saw-tooth configuration, comprising crimps 29, 30, 31, 32 and 33 generally in the XY plane of FIG. 8. In FIG. 9 it can be seen that after the second crimping the filament 22 is crimped more randomly and without large lengths wholly devoid of crimp. The crimp 30, for example, has had impressed therein a sub-crimp 30a which has been deflected out of the XY plane toward-the XZ plane. Sub-crimp 31a has been formed out of a comparatively straight seCtion'of crimp 31 and is generally directed in still another plane. other crimps are similarly affected so that a filament-of higher crimp and bulk is achieved.

Each crimper 15, 19 can generally impart from about 3 to 15 crimps per inch of an amplitude ranging from about 0.5 to 4.0 mm. and'the two crimpers are conveniently synchronized in' speed so that the second operates a little more slowly than the first but sufficient to receive the filaments at the same rate they are discharged from the first crimper. For example, the tow may be fed to the first crimper at the rate of 400 meters per minute and, to compensate for shrinkage due to crimping, it may be fed to the second crimper at the rate of 250-300 meters per minute. A reserve of filaments can be provided before the second crimper to compensate for any minor variations in feed rate. Because of the irregular crimping action of each crimper, the second crimper can produce deviations in the XY plane itself, thereby modifying the generally sinusoidal patternwithin that plane. The

successive crimpings need not be performed in tandem but instead the tow can be collected after the first crimping and can then be lubricated and again crimped at a different rate, further to modify the crimp pattern. The preferred method is to subject to a first crir'npingoperation to impart from about 5 to 8 crimps per inch of an amplitude of 0.5 to 4.0 mm. and subjecting the initially crimped tow-to at least one additional crimping operation by a stufiing box crimping capable of imparting 5 to 8' crimps per inch of an amplitude of 0.5 to 4.0 mm. to the tow when uncrimped.

The multi-crimping in accordance with the present invention will serve to increase the total crimp'of the fila inch, i.e. two, and the amplitude it will be equal to the In determiningthe distance between peaks and valleys. crimps per inch of an already crimped fiber, the peaks are first counted, the fiberis tensioned so as to be straight,

and the straight'length of the fiber is determined. The

number of peaks divided by the straightened length in inches is the number of 'crim-psper inch.

The sequence of treatments indicated can be varied in that the tow can first be cut into staple fibers, formed into a sliver and then double-crimped or the cutting can take place after the first crimping operation but before the second crimping operation.

sliver.

The invention is generally applicable to filamentary materials of various kinds including synthetic polyamides such as polyhexamethylene'adipamide' and poly-aminocaproic acid, polyesters such as polyethylene terephthalate, polyurethanes, polyaminotriazoles, and polymers and copolymers of vinyl chloride such as vinyl chloride-vinyl acetate copolymers. It is eminently suited for the treatment of organic derivatives of cellulose, including, for example,.cellulose acetate,.cellulose propionate, cellulose Portions of the" The lubrication in thesemodifications can be applied either to the tower the butyrate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, cellulose benzoate, and ethyl cellulose. In the cellulose derivatives the hydroxyl groups of the anhydroglucose units of the cellulose molecules can be substantially completely replaced as in cellulose triacetate or they can be partially replaced as in ripened cellulose acetate wherein about 0.6 free hydroxyl group per anhydroglucose unit is present.

The following examples are given to illustrate the invention further.

EXAMPLE I A tow comprising 30,000 filaments of cellulose acetate having an acetyl value of 55% by weight calculated as acetic acid, each filament of which is 5.5 denier and Y- shaped in cross-section, finished with about 1.5% by weight of the composition of Example III of Fortess et al. Patent No. 2,676,924, is passed first through a stufiing box crimper operating to impart thereto about 7 crimps per inch of an amplitude varying between 0.54.0 mm. The crimped tow then is wet with water and passed through a second stuffing box crimper which increases the crimp to about 9 crimps per inch of an amplitude varying between 0.5-4.0 mm. The tow is then cut into staple fibers about 1 /2 inches in length. The specific volume of the staple fibers when placed in a vessel and put under a pressure of 2.5 pounds per square inch is about 0.75 cubic inches per gram whereas if the second crimping operation is omitted the specific volume is about 0.70 cubic inches per gram.

EXAMPLE II The procedure of Example I is repeated, substituting for the lubricant there described a quaternary ammonium lubricant sold under the trade name of Ahcovel. The staple fibers which are almost of equal specific volume are bright and have a very soft, luxurious hand.

EXAMPLE III By the process of Example I, cellulose acetate filament yarns spun through orifices of different shape and each 4 denier per filament were double crimped and cut into staple fiber. The relative specific .volumes are indicated in the following table:

A tow was formed of cellulose acetate filaments spun through a 70-hole jet having pentagonal orifice-s and another 70-hole jet having triangular orifices, each filament being 8 denier. The tow was processed as in Example I to produce double-crimped staple fibers having a specific volume of 0.6 cubic inch per gram as opposed to a specific volume of 0.5 cubic inch per gram for regular staple.

EXAMPLE V A tow comprising 5000 cellulose acetate 16 denier filaments, having an acetyl value of 55 is finished and crimped as in Example I and the tow is collected in a bale. The baled tow is then processed into cigarette filter plugs as shown in FIG. 11. As compared with a tow singly crimped, the double crimped tow is much more uniform and opens more uniformly. The novel filters are firm, uniform and free of random soft spots.

EXAMPLE VI The process of Example V is repeated with the sole difference that the tow is made up of '8750 filaments of 8 denier each. The resulting filters are uniform and very firm. If the flapper pressure of the stuffing box crimpers is reduced to insert only 6 crimp-s per into into the tow, the resulting filters are of excellent uniformity and their firmness compares favorably with that of filters from a tow crimped to a higher level in a single stage.

This application is a division of application Serial No. 833,230, now US. Patent No. 3,093,142 which in turn is a continuation-in-part of application Serial No. 675,120 filed July 30, 1957, now US. Patent No. 2,968,857, issued January 24, 1961.

It is to be understood that the foregoing detailed description is merely given by way of illustration and that many variations may be made therein Without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. The process which comprises forming a tow of continuous filaments wherein the individual filaments are less than about 25 denier, subjecting said tow to a first crimping operation to impart from about 5 to 8 crimps per inch of an amplitude of 0.5 to 4.0 mm., subjecting said tow to at least one additional crimping operation by a stuffing box crimping capable of imparting 5 to 8 crimps per inch of an amplitude of 0.5 to 4.0 mm. to said tow when uncrimped, thereby to impart to said filaments of said tow a three-dimensional structure of high bulk with the crimps extending in a plurality of planes, and forming said tow into cigarette filters.

2. The process set forth in claim 1 wherein at least some of said filaments are formed by extrusion of filament-forming material through non-circular orifices.

3. The process set forth in claim 1 wherein at least some of said filament-s are Y-shaped in cross-section.

4. The process set forth in claim 1, wherein said filaments comprise an organic acid ester of cellulose.

5. The process set forth in claim 1, wherein said tow is wet prior to each crimping operation.

6. The process which comprises extruding through triangular orifices a solution of cellulose acetate in a volatile solvent to form a tow composed of filaments Y-shaped in cross-section and said tow composed of continuous filaments wherein the individual filaments are less than about 25 denier, wetting said tow, subjecting said tow to a first crimping operation to impart from about 5 to 8 crimps per inch of an amplitude of 0.5 to 4.0 mm., again wetting said crimped tow, subjecting said tow to at least one additional crimping operation by a stufi'ing box crimping capable of imparting 5 to 8 crimps per inch of an amplitude of 0.5 to 4.0 mm. to said tow when uncrimped, thereby to impart to said filaments of said tow a threedimensionalstructure of high bulk with the crimps extending in a plurality of planes and forming said tow into cigarette filters.

7. The process set forth in claim 6, wherein said tow comprises about 3000 to 40,000 filaments of about 50,000 to 250,000 total denier.

References Cited by the Examiner UNITED STATES PATENTS 1,356,148 10/1920 Hobert 5355 1,389,715 9/ 1921 Van Gelder 5-355 2,326,174 8/ 1943' Ruthishauser 1966 2,669,001 2/ 1954' Keen '2872 2,715,309 8/ 1955 Rosenstein 57140 2,794,239 6/1957 Crawford et al. 2,818,630 1/1958 Le Boeuf 28-72 2,829,027 4/1958 Raynolds et al. 2,900,988 8/1959 Crawford et al. 2,968,857 1/ 19 61 Swerdlotf et al. 28-72 3,017,309 1/ 1962 Crawford et al.

DONALD W. PARKER, Primary Examiner. RUSSELL C. MADER, MERVIN STEIN, Examiners. L. K. RIMRODT, Assistant Examiner. 

1. THE PROCESS WHICH COMPRISES FORMING A TOW OF CONTINUOUS FILAMENTS WHEREIN THE INDIVIDUAL FILAMENTS ARE LESS THAN ABOUT 25 DENIER, SUBJECTING SAID TOW TO A FIRST CRIMPING OPERATION TO IMPART FROM ABOUT 5 TO 8 CRIMPS PER INCH OF AN AMPLITUDE OF 0.5 TO 4.0 MM., SUBJECTING SAID TOW TO AT LEAST ONE ADDITIONAL CRIMPING OPERATION BY A STUFFING BOX CRIMPING CAPABLE OF IMPARTING 5 TO 8 CRIMPS PER INCH OF AN AMPLITUTDE OF 0.5 TO 4.0 MM. TO SAID TOW WHEN UNCRIMPED, THEREBY TO IMPART TO SAID FILAMENTS OF SAID TOW A THREE-DIMENSIONAL STRUCTURE OF HIGH BULK WITH THE CRIMPS EXTENDING IN A PLURALITY OF PLANES, AND FORMING SAID TOW INTO CIGARETTE FILTERS. 